[Bug libstdc++/105681] New: libstdc++-v3 fails to build on msp430

[beagleboard at davidjohnsummers dot uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105681

            Bug ID: 105681
           Summary: libstdc++-v3 fails to build on msp430
           Product: gcc
           Version: 12.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: beagleboard at davidjohnsummers dot uk
  Target Milestone: ---

Hi, I'm trying to build gcc for an msp430 cpu, using gcc12.1.0 binuitils-2.38
and newlib-4.2.0.20211231. Now I can build c fine, but when I try to build c++
libstdc++-v3 fails, I think becuase the msp430 is only a 16bit processor.

The specific configure command used is:

../../gcc-git/configure --with-sysroot=/home/summers/msp430
--prefix=/home/summers/msp430  --target=msp430-elf --disable-nls
--disable-werror
--with-native-system-header-dir=/home/summers/msp430/msp430-elf/include
--with-newlib --enable-languages=c,c++ --disable-nls --enable-initfini-array
--enable-target-optspace --with-gmp --with-mpfr --with-mpc --with-isl
-enable-newlib-nano-malloc

This has binutils and newlib copied into the gcc source directory. The native
system header is pointed at newlib header files.

The build fails with errors like:

In file included from
/home/summers/msp430/gcc-git/libstdc++-v3/include/precompiled/extc++.h:61:
/home/summers/msp430/src/gcc-binutils-newlib/msp430-elf/libstdc++-v3/include/ext/random:355:69:
error: narrowing conversion of '86243' from 'long int' to 'unsigned int'
[-Wnarrowing]
  355 |                                             0x00000000U, 0xe9528d85U>
      |                                                                     ^

I also tried the build with the git version of gcc, last weekend (14/5/22) and
had exactly the same error.

So is this a bug, or have I configured something wrong. Does libstdc++-v3 just
need to be made 16bit aware?